Gummed tape manufacture



Jan. 30, 1940, H. F. BAUER ET AL 2,188,329

GUMMED TAPE MANUFACTURE Filed Dec. 22, 1958 Patented Jan. 30,'.19401 PATENT or-'Flor'.

Gump rara monarcas Ham F. Bauer, Chicago, Jordan V. Bauer,'Elm v wood Park,Y and Don M. Hawley, Geneva, lll.,

aaaignors to Stein, Ball Manufacturing Company, Chicago, lil., a corporation of Delaware application December zz, 193s, serial No. 241,138

iz claims. l21. :i1-ss) This invention relates to improvements in gummed tape manufacture and. more particularly to a new and improved type of remoistening tape and to a new and improved method for the manufacture thereof.

In our. copending application, Serial No. 226,-

074, filed August 22, 1938, now Patent No. 2,144,-

' 610, we have described a new and improved type of remoistening tape containing an amylaceous adhesive. The term amylaceous adhesive" is employed to refer to those types of adhesives which are prepared from starches and starch degradation products such as dextrinesl and starch gums. The expres-sion` ,remolstening tape containing an amylaceous adhesive is employed to describe paper or fabric, or combinations of paper andfabric, inthe 4form of a strip containing on one vside thereof an adhesive which, on

being moistened, willimmediateiy develop tacklness and act as a suitable adhesive for bonding the 'paper or fabric to other materials.

At present large amounts -of 'gummed paper suitable for suchpurposes as labels, stamps and envelope seals are prepared with dextrine adhesive, lbut dextrine adhesives have never been suc` cessful in replacing animal glue adhesives in the neldrof gummed tape for sealing the heavier types of boxes or for gummed paper or fabric which is to be used for purposes wherein itis required that the adhesive coating on being re- -moistened will develop immediately strong adhesive properties and set up very rapidly to form hesives could be satisfactorily used. The base material from which this tape is made may be described as an incompletely dextrinized 'starch or British gum converted to a solubility of at least about in water at 75 F. and a dextrine content of less than 55%, as determined by 5o the method of Babington, Tingle and Watson. See The examination of commercial dextrine and related starches, Babington, Tingle and Watson, Journal of the Society of Chemical Industry. 37 (1918) 257. One of the objects of this invention is to provide a new and improved type of gummed tape containing a different type of vegetable remoistening adhesive than heretofore employed and characterized by such exceptional adhesive strength that the tape is suitable for the 5 strongest types of .adhesive applications. Other objects will appear hereinafter.

We have found in accordance with this invention that we are able to prepare superior remoistening tapes which develop extreme tacki- 10 ness immediately on being remoistened, do not tend to slip or slide on the surface to which they are applied even under conditions of considerable tension or sidewise pressure and have sunl- `cient cohesiveness while still wet to hold sur- 15 auxiliary materials as hereinafter more fully de- 20 scribed.

In our copending application previously referred to we have employed for gummed tape manufacture a base material having a dextrine content of less than 55% as determined by the -25 Babin'gton, Tingle and Watson test and a relatively high solubility. In accordance'with the present invention we have found that we may use amylaceous base materials of certain specined types having certainv specined iluidities and. 3b

a relatively lowwater solubilityprovided said materials are utilized in commotion with auxiliary materials as more fully hereinafter described.

The accompanying drawing pictures the ad- 35u hesive coated sheet.

Our base materials for the purpose of the present invention are derived from root starches, as, for example, sago, sweet potato, tapioca and potato, which have been converted to the fol- .40 lowing characteristics: v

(a) A vdextrine content of less than 55%, as determined by the Babington, Tingle and Watson test. The following method of determining desarme content is the method of Babington, 4

'Iingle and Watson, as described in the Journal of the Society of Chemical Industry, supra:

The sample (1 grm.) is warmed in a 100 cc.

graduated flask with 30'cc. of water until just gelatinized and cooled quickly:` 50 cc. of a cold 50 saturated barium hydroxide solution is next added (the flask being meanwhile shaken), followed by enough water -tobring the total volume to cc. The solution is filtered through a dry 15 cm. paper and an aliquot portion (50-55 on a water bath. The sand should be stirred when almost dry to expose the maximum surface to the air, after which the dish is transferred to a well regulated oven and dried to constant weight at 120 C., below which temperaturecrystallized barium chloride is dehydrated.

Dextrin gum being hygroscopic, precautions must be taken accordingly. The dish is now heated strongly, but not beyond the temperature necessary for the complete combustion of the organic matter. During ignition the sand should be well stirred at intervals to allow full exposure to the air. The dish and contents are then cooled and weighed. The difference in weight before and after ignition represents the dextrin gum in cc. of ltrate, i. e., in half the weight of sample taken.

(b) The viscosity of degraged or dextrinized starches is a denite indication of the extent to which the starch has been dextrinized or degraded. We use a range of viscosity specifications to further dene the type of dextrinized starch product which is suitable for our purpose, and we nd that a dextrinized or degraded starch to be satisfactory for our purposes should, when cooked in proportions of one part of degraded starch to one and one-half (l1/2) parts water to 190 F. and then cooled to 125 F. giving a viscosity reading Within the range of fteen (15) seconds to four hundred (400) seconds, preferably within the range of twenty-five (25) seconds to one hundred and fifty (150) seconds on the Stormer viscosity apparatus, the readings in question being the time for one hundred (100) revolutions of the viscosimeter cylinder using a one hundred gram (100 grin.) Weight. The

Stormer viscosimeter used gave a reading'of 5.6

seconds with water at 125 F. and a reading of 2.4 seconds running free with the viscosimeter cup emptied, these readings being the time required at 100 revolutions of the viscosimeter cylinder, using a one hundred gram (100 grm.) weight.

'I'he Babington, Tingle and Watson test specication of less than dextrine content as given under (a) dei'lnes approximately the greatest degree to which the starch may be dextrinized or degraded and still be satisfactory for our purpose, whereas, the upper limit of 400 seconds 'Stormer viscosity at 125 F. denes approximately the lowest degree to which the starch may be degraded or dextrinized and yet be satisfactory for our purpose.

(c) Within the limits given under (a) and (b) we may employ conversion products derived from root starches having a solubility within the range of about 3% to about 50% in water at '15 F.

It should be understood thatl degraded or dextrinized starches somewhat outside the ranges we specify may, when used in the manner we disclose, function as remoistening adhesives. The limits given above, however, approximately dene the range of amylaceous materials which we have found most suitable for this purpose.

It is known in the adhesive art that incompletelyy dextrinized starches give stronger and 2,1ss,sao

tougher adhesive lms than those types of dextrine products which have been more completely dextrinized. Prior to our invention it has not been possible, however, for the purpose of remoistening tapes to take full advantage of these desirable properties of sols prepared from incompletely dextrinized starches, probably due to the tendency of the more incompletely degraded portions of these materials to retrograde to a less soluble state, which when in the form of a dried film Will not remoisten with sufcient rapidity to be suitable for thoseusages to which remoistening adhesives are applied. We have found, however, that by the use of an amylaceous base material Within the solubility range and dextrine content above specied in conjunction with cer- .tain additional materials which apparently function as a solvent for the more incompletely degraded portions of the amylaceous base material and counteract the retrogradation of these portions to a less soluble form it is possible to prepare remoistem'ng adhesives that have superior adhesive properties and yet remoisten with the extreme rapidity that is necessary for gummed tape applications. Among the materials which have this solvent'action are urea, thiourea, ammonium nitrate, sodium nitrate, guanidine nitrate, potassium nitrate, potassium thiocyanate, and sodium thiocyanate. These materials also apparently act as plasticizing agents, tending to inhibit the formation of checks or cracks and they may be used in preparing gummed tape in accordance with our invention with or without additional plasticizing agents, as, for example, glycerine, ethylene glycol, diethylene glycol and other polyhydric alcohols, or With sodium lactate and other substances having a plasticizing action. In general, we prefer to employ about 3% to about 30% of a solvent plasticizer of the character previously described, with or Without about 1% to about 10% of a non-solvent plasticizer such as glycerine, polyhydric alcohols or other plasticizers. Of the solvent plasticizers previously mentioned, we prefer to employ water soluble ureas because of the unusually good results, the fact that they are non-toxic and are substantially neutral. Excellent results may be obtained, however, with the other solvent plasticizers mentioned.

The term a water soluble urea is employed herein to cover generically urea and its water soluble analogues and homologues, including thiourea. 'I'he expression a Water soluble thiocyanate" is .used herein to cover the thiocyanates mentioned and other Water soluble thiocyanates. The term a water soluble nitrate is used herein to cover the nitrates mentioned and other water soluble nitrates.

In addition to a solvent plasticizing agent, as previously described, we also include in our remoistening adhesives a relatively small amount of borax, or other similar material which is adapted to increase the tackiness and viscosity of amylaceous dispersions. To supplement the value of our gummed tape prepared in the manner herein described, we may add borax and Various other materials such as alkalis, wetting agents, solvents and the like to the remolstening water. Sodium aluminate and similar soluble aluminates function somewhat similarly to dorax in increasing the viscosity of amylaceous dispersions. We may also form our viscosity increasing agent in situ in the adhesive composition, for example, by incorporating in the adhesive boric acid and adding an alkali in the remoistening water, or some other compound adapted to react with boric acid toform a soluble borate. Thus. if4 boric acid is incorporated into the remoistening adhesive, a small amount' of caustic alkali Vmay beincluded in the moistening water to form sodium borate in situ. l

It is wen knownto the adhesive art that the addition of borax to dextrine or starch zum .sdf

hesives increases their tackiness and viscosity,

Because of this fact, a greater percentage of the dextrine vand starch gum adhesives used today wherein' the adhesive is applied in liquid or paste form and allowed to dry in situ between the surfaces to be'bonded contain borax or mixtures of borax with otherV alkaline materials. It'has .not

been practical, however, to use borax in those4 types of dextrine or starch gum adhesives which are used for remoistening purposes due to the fact that when films of dextrine or starch gum adhesive containing borax are dried they do not for such purposes as ythose to which gummed ucts and may be addeddirectly to the adhesive with a very'decided improvement in remoisteningy characteristics provided a relatively small amount, as, for example, 1% to 10%, and pref# erably less than %l is employed, and provided further that a modifying agent .is used to4 modify the action of borax upon lthe starch. Wehave found that solvent plasticizers of the type pree viously mentioned, as well as glycerine, and other types of hydroxyl carrying plasticizers such as polyhydric alcohols have this modifying action and lmaire the use of borax possible. For our purpose, however, we prefer that the plasticizing and modifying agent be present at least partially -in the form of a normally solid solvent plasticizer f of the type previously described rather than en- 1 tirely in the form of a normally liquid relatively hygroscopic plasticizer such as glycerine, because `the latter tends to destroy to some extent the adhesive and tackiness properties particularly when'used inl relatively large amounts.

We usually prefer that the amount of borax or other viscosity increasing agent be not greater .than the amount of plasticizer. .We have found,

for example, that for vthe best results, where glycerine is used as a plasticizer, the amount of glycerine should be in excess of the amount of borax. I

By the use of the speciilcally dened combinal tion of materials we herein disclose we are able to produce a remoistening adhesive tape at least equivalent in adhesive properties to the better grades of animal glue remoistening adhesive tapes. Furthermore, bythe use in conjunction with the above adhesive combination of the second, or supplementary means of our invention, n

namely, the introduction -of borax or other viscosity increasing agent into'the water used to remoisten the adhesive nlm, it is possible vto obtain adhesive results far superior to animal glue remoistening adhesives.

We-realize that the use of urea in conjunction with the more completely degraded dextrines and in certain instances' with starches is not new.

We believe, however, that our useof urea and other solvent plasticizers of the type defined in conjunction with a starch conversion product of the type herein deilned is novel for the purpose of remoistening adhesive tape and produces new and improved results. v

The un'i results-'of our invention cannot be lobtained bythe mere use of urea in condunction. with any random type of degraded or dextrinized starch product. Theprior art, to our knowledge, doesv not teach the value or use of urea and other solvent p lasticizers with a starch degradation product within the range Vwe define for the purpose of a superior rernoistening adhesive tape. Y vi The general type of remoistening tape covered by the present invention is illustrated in the -ac'- vcompanying drawing in which,`asi llustrated, an

adhesive is applied as a coating to a paper strip. It will beunderstood that instead of a paper strip. a fabric Astrip may be employed. or alternatively, the strip may consist of a fabric backed paper strip in which the exposed surface of the paper 'contains an adhesive iilm. In general, the present invention is especially adapted to the manufactureof gummed tape in'which the base mal terial is a cellulosic sheet material such as paper.

vWe illustrate below several of our preferred adhesive formulae and a comparison of their adhesive properties with other types of remoistening adhesives as indicated by the McLaurin gummed tape tester. The adhesive samples were prepared in the .manner specified and ap' plied to kraft paper under uniform conditions equivalent to present commercial practice. The prepared samples of tape were then tested under uniform conditions en the McLaurin gummed tape tester, according'to the method specified by the Thwing-Albert Instrument Company, Philadelphia, Pennsylvania, makers of theabove instrument. It'will be understood that the results of this test mayvary somewhat depending upon humidity and temperature conditions, but the comparative results definitely showed the superi-V ority of the gummed tape made in laccordance with our invention.

The readings obtained with the better grades of animal glue tape run as anaverage between The above materials were mixed together and cooked to'a temperature of 180 F. The mixture was then cooled to F. and applied to the paper and dried. It may be applied either hot or cold. The tapioca conversion product used was one having .a dextrine content of 9% as determined by the method of Babington, Tingle and Watson,

' a solubility of about 12.6% and a fluidity of 38 seconds, as determined on a Stormer viscosim'eter in the manner previously described.

After being allowed to air dry for four days the McLaurin tests on this tape when moistened with water averaged about '19. VA McLaurin test of 92 was obtained when the tape was moistened with a saturated solution of borax.

Example 1r A composition was the same as that described in Example I except that the tapioca conversion l product employed had a dextrine content of 20%,

a solubility of 23% and a fluidity of 23 seconds. The mixture was prepared and applied to paper tape in the same manner as described in Example I.

After air drying four days the McLaurin test on tape prepared in this manner with this composition averaged about when remoistened with water.

y Example III Example IV Parts Tapioca conversion product 97 Borax 3 Sodium nitrate 20 Water Glycerine 5 The above materials were mixed together and cooked to a temperature of about 180 F. 'Ihe mixture was then cooled to 80 F. and applied to paper and dried. The tapioca conversion product was the same as that described in Example I. having a dextrine content of 9%, a solubility of about 12.6% and a fluidity of 38 seconds as determined on a Stormer vscosimeter in the manner previously described.

After being allowed to air dry for four days the McLaurin test on this tape when moistened with water averaged about 78. A higher test was obtained when the tape was moistened with a saturated solution of borax.

Example V Parts Tapioca conversion product 100 Urea 25 Borax 3 Water 95 Glycerine 5 These ingredients were mixed together and cooked to a temperature of F. The mixture was then cooled to 80 F. and appliedto the paper and dried. The tapioca conversion product used was the same as that used in Example I.

After being allowed to air dry for four days the McLaurin tests on tape made in this manner averaged about 83.4. For comparison a similar tape was prepared except that borax was omitted from the composition. In this case a McLaurin test of only 28.8` was obtained. In this second tape the use of a saturated borax solution as the remoistening agent increased the McLaurin test to 50.1. The use of a saturated borax solution as the remoistening agent on the rst tape increased the McLaurin test to 91.8. 'I'hese results illustrate the importance of borax in the adhesive composition.

'I'he following example is given to show the results obtained with corn conversion products as distinguished from tapioca conversion products, or conversion products made from other root starches: Y

Example VI Parts Corn conversion product 100 Urea 25 Borax 3 Water 95 Glycerine 5 The above vingredients were cooked to about v 180 F. then coded to about 80 F. and appued to paper and dried.

'Ihe McLaurin tests on this tape averaged about 35.8 when moistened with plain water and about 57.4 when moistened with a saturated solution of borax. 'I'he corn conversion product employed in making this composition had a solubility of about 11.6%. a dextrine content of 10% and a fluidity of 43 seconds. 'Ihis example illustrates, however, that the corn conversion products are inferior to tapioca conversion products.' or conversion products obtained from other root starches, as distinguished from grain starches. On the other hand the compositions made from corn conversion products may be useful where a borax solution or a solution of another viscosity increasing agent is employed to remoisten the tape.

The following example is given to illustrate results obtained when the remoistening adhesive' is prepared from an ordinary type of tapioca dextrine such as is now used in the art for preparing adheslves for stamps, labels and the like.

The above materials were mixed together and cooked to a temperature of F. then cooled to a temperature of 80 F. applied to paper tape and dried.

The taploca dextrine was one having a solubility of 98% at '15 F. and a dextrine content as determined by the method of Babington, 'Ingle and Watson of 96%. The MaLaurin test on tape prepared with this adhesive composition averaged about 16 when 'moistened with water and about 29 when moistened with saturated borax solution.

Comparison of this example with Examples I to V indicates the importance of using an amylaceous base material of the type herein defined. It should be noted that by the use of our supplementary means of incorporating borax in the remoistening Water. the adhesive properties of prior art types of adhesives can be substantially improved. i

It should be understood that these various examples of adhesive formulae given above are for the purpose ofillustrating the novel character of our invention and for the clear the principle and the relative value of the means by which we obtain our result.

We. therefore, do not wish to be limited by the specific examples herein disclosed, inasmuch as numerous kvariations may be made in the character of the adhesive base and in the proportion of other ingredients used without departing from the limits we define as essential for the purpose of making :,isasaa with that disclosed incur copending application Serial No. 226,074 may be greatly increased by the addition to the adhesive composition of small amounts of addition agents such as water soluble condensation products or resins. -Among the ati--` ditional agents which We have found to greatly increase the retacking properties and substantially increase the McLaurin test is a product made by Du Pont and sold in the trade as Rayon Size MW Mod. 90568. Water soluble substances of this type may be used in effective amounts, preferably up to around 5%', excellent results being obtained with as little as 1%, based on the weight of the adhesive composition.

In such instances where it is desirable our disclosed adhesive compositions may be mixed with compatible adhesive materials made from animal glue, iish glue, casein, starch, natural gums andwater soluble natural or synthetic resins.

Gummed tape made in accordance withV the present invention develops extreme tackiness irnmediately upon being remoistened and is characterized by a very high rapidity of set. As contrasted with animal glue tapes it has practically no odor. One of the further features of this ytape resides in the fact that the adhesive contained thereon is substantially neutral and con tains no ingredients which are harmful tov paper or fabric or to the user in case the gummed tape is moistened with the tongue. Additionally, the

adhesive film is extremely flexible and does not Ireadily check, crack or chip oi! vwhen the tape is exed.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

- 1.v A remoistening tape of the character described comprising a exible cellulosic sheet material in the'form of a dried coating thereon of a water pervious vegetable adhesive layer consisting mainly of a root starch conversion product converted to a solubility within the range of about 3% to about 50% in water at 75 F., a viscosity within the range of 15 seconds to 400 sec-v onds, as determined in the manner herein described and a dextrine content less than about 55% as determined'in the manner herein described, intimately dispersed with about 3% to about 30% urea based upon the weight of said conversion product,l about 1% to about 5% borax` and about 1% izo-about 10% glycerine, said adhesive possessing strong adhesive properties and being capable when moistened of developing tackiness and setting rapidly.

2. A remcistenmg tape of the character 'described comprising on at least one surface thereof a water pervious layer of adhesive consisting mainly of an incompletely dextrinized starch converted to a solubility of from about 3% to about in water at '15 F., a viscosity within the range of about 15 seconds to about 400 seconds, as

mainly of a root starch converted to a solubility borate in effective amounts upto about 10% and the insolubilizing action of the bor-ate on the con-V version product.

3. Aremoistening tape of the character -de scribed comprising on at least one surface' thereof a water pcrviouslayer of adhesive4 consisting mainly of a root starch conversion product converted to a solubility of from about 3% to about 50% in water at 75 F., a'viscosity withinl the range of about 15 seconds to about 4 00 seconds, as determinedin the.' manner herein described, and adextrine content below about as determined in the manner herein described, intimately dispersed with about 1% to about 10%' l' of a soluble borate and aboutr3% to about 80% of a plasticizing agent.

4. A remoistening tapel of the' character described comprising on at least one surface thereof a water pervious layer'of adhesivel consisting within the range cf about 3% tc about 50% in water at F., a viscosity'within the range of 'about 15 seconds tc about 40o seconds, is-deter-v mined in the manner herein described, anda dextrine content less than about 55% as deter-` 25 mined in the manner herein described, intimately dispersed with about 1% to about 10% of a soluble berate and about 3% tc about 30% of c plasticizinlg agent, the amount of plasticlmng agent being greater than the amount of borate.

5. A remoistening tape of the character described comprising on at least one surface ,thereof a water pervious layer of adhesive consisting of a root starch converted to a solubility of about 3% 55%, as determined in the manner herein del scribed, intimately dispersed with a sOluble about 3% to about 30% of a solvent plasticizer for said conversion product.

6. A remoistening tape of the character described comprising'on at least one surface thereof a water pervious layer of adhesive consisting mainly of a root starch converted to a solubility of from aboutV 3% to about 50%in water at-75 F., a viscosity within the range of about 15 seconds to about 400 seconds, as determined in the man-V ner herein described, and adextrine content less than about 55%, as determined in the manner herein described, intimately dispersed with a soluble borate Vin effective amounts up to about 10%, about 3% to about 30% of a'normally solid plasticizer for said. adhesive composition having a solvent action on said oonverstlon product and about 1% to about 10% of alnormally liquid plasticizer, said percentages being based upon the weight of the conversion'product. Y

7. AA remoistening tape of the character described comprising on at least onesurface thereof a water pervious layer of adhesive consisting mainly oi' a root starch converted to a solubility offrom about 3% to about' 50% in water at 15? F., -a viscosity within the range of about 15 sec onds to about A400 seconds, as determined in the -manner herein described, and a dextrine content less than about 55%, as determined in-the manner herein described, intimately dispersed with about 1% to about 5% of a soluble'borate and a solvent 70 plasticizing vagent for said conversion product-in minimum' amount o f about 37%, said solvent plasticizing agent being effective in inhibiting the insolubilizlng Vaction of saidboratc on the oonversionproduct. Q n

' yoi.' about 15 seconds to about 400 seconds, as determined in the manner herein desscribed, and a dextrine content less than about 55%, intimately dispersed with a viscosity increasing agent in minimum amount of about 1% and a plasticizing agent in minimum amount of about 3%.

9. A remoistening tape of the character described comprising on at least one surface thereof a water pervious layer of adhesive formed from aroot starch converted to a solubility of about 3% to about 50% in water at '15 F., a viscosity within the range of 15 seconds to 400 seconds, as determined in the manner herein described, and a dextrine content less than about 55%, as determined jin the manner herein described, intimately'dispersed with a viscosity increasing agent in eiective amounts to increase the retack properties oi said adhesive and a plasticizing agent in eiective amounts to inhibit checks and cracks in dried lms of said adhesive.

l0. A remoistening tape of the character described comprising on at least one surface thereof a water-pervous layer of adhesive formed from a root starch converted to a solubility of about 3% to about 50% in water at '15 F., a viscosity within the range of about 15 seconds to about 400 seconds, as determined in the manner herein described, and a dextrine content less than about 55%, as determined in the manner herein described, intimately dispersed with a water-soluble urea in amounts-from about 3% to abcut 30% by weight of said starchconversion product.

11. A remoistenlng tape of the character described comprising on atleast one surface thereof a water-pervious Vlayer,l of adhesive consisting mainlyof a root starch converted-to a solubility Y of about 3% to about 50% in water at 75 F., a

viscosity within the range ofabout 15 seconds to about `400 seconds, as determined inthe manner herein described, and a dextrine content less than yabout 55%, as determined in the manner herein described, intimately dispersed with a normally solid plasticizingy agent having a solvent action on said root starch conversion product in amounts eilective .to produce an adhesive of strong re-tack properties and to inhibit cracking oiI of dried coatings of said adhesive. ,i

l2. A remoistening tape of the character described comprising on at least one surface thereof a layer of adhesive consisting mainly of an in- -completely dextrinzedamylaceous conversion product converted to a solubility of about 3% to about 50% in'water at 75 F., a viscosity within the range of about 15 seconds to about 400 seconds, as determined in the manner herein de- 

